Decorative and structural panels for architectural and transport vehicle applications commonly have a decorative laminate outer cover affixed to a substrate. Decorative laminates are typically constructed with an exterior surface that is either an embossed texture, print pattern or both aesthetic design features. The decorative laminate is then formed and adhered to an underlying structural substrate layer. Maintaining uniformity of the texture and print pattern design features of the decorative laminate throughout the manufacturing process is very important.
Generally, such laminates are constructed using multiple layers of various films laminated together under high temperature and pressure, and/or embossed (again at high temperature and pressure) at different stages in a continuous roll-forming manufacturing process. U.S. Pat. No. 5,976,671 discloses two conventional constructions of a decorative laminate. In the first construction, the decorative laminate possesses two layers: a first embossed layer that imparts surface release to the laminate and a second decorative layer that overlies the first. This decorative layer is typically either screen printed (i.e., multi-graphics) or integrally colored (i.e., internally pigmented). Generally, the single laminate includes a textured layer consisting of a thermo-setting or thermoplastic emboss resin overlayed with a decorative layer composed of a thin layer of pigmented thermo-plastic film.
Other prior art teaches a second type of construction for a decorative laminate with an embossed layer, a decorative layer, and at least one structural layer. Conventional methods for the manufacture of such laminates are limited by the properties of the materials used which impose limitations on the extent to which the combined layers can be heated, stretched and further processed in casting and roll-forming machinery without adversely affecting the dimensional stability of the final product.
Present materials and manufacturing techniques do not enable the manufacture of a non-reinforced laminate in a continuous lamination process which results in a laminate having low distortion or dimensional stability. Laminates have three basic dimensions which can be represented by reference to x, y, and z axes, where the z-axis represents the thickness of the laminate. In conventional laminates, permanent distortion occurs along the x or y axis, or both, when the laminate is heated and stretched in one or more directions as a result of forces applied in a mechanical lamination process such as roll-forming. As the laminate cools it retains such distortion. Further, decorative laminates manufactured with materials and manufacturing techniques currently known result in a laminate, which when applied to a substrate under heat and vacuum, transmits defects in the substrate and loses texture retention. Therefore, a need exists for a laminate producible from materials with the desired aesthetic properties of texture and graphical features, and which does not distort or deform dimensionally in a roll-forming manufacturing process.
Some polymer films which are used as layers in laminates are provided with a pre-applied layer bonded directly to the polymer film by one of several conventionally known methods such as solution casting. In laminating and roll-forming techniques used in the art, films with no or low-orientation have relatively high elongation and shrinkage at temperatures required for embossing, which makes creating a laminate product in a continuous roll difficult. It is standard practice in the art to remove carrier layers prior to lamination of the polymer film to any other layer in a roll forming process, primarily so that the carrier does not interfere with the processing, e.g., bonding and texturing, of the polymer film. Removal of the carrier however, allows the film to deform or distort in multiple dimensions, particularly when the laminate is mechanically processed. Distortion is magnified by additional layers in the laminate.